1. Field of the Invention
The present invention relates to a liquid droplet jetting apparatus which jets a liquid droplet of a liquid from a liquid droplet jetting head.
2. Description of the Related Art
In conventional liquid droplet jetting apparatuses for jetting liquid droplets, there are many liquid droplet jetting apparatuses each of which is provided with a waste liquid recovery device recovering an unnecessary liquid (hereinafter referred to also as “waste liquid”) discharged for example during maintenance for the liquid droplet jetting head. Each of the waste liquid recovery devices of general type has a waste liquid case and an absorbing body (absorbing member) which is formed of a porous material, which is accommodated in the waste liquid case and which absorbs the waste liquid.
Among such waste liquid recovery devices of the general type, there is known a waste liquid recovery device configured to be capable of detecting whether or not the waste liquid is absorbed into the absorbing body up to a full liquid state, in order to prevent the waste liquid from overflowing from the waste liquid case. For example, Japanese Patent Application laid-open No. H08-104014 and Japanese Patent Application laid-open No. 2002-283588 each disclose a technique in which a pair of electrodes is provided on an absorbing body at a predetermined full-liquid detection position thereof; and whether or not the liquid arrives at (reaches) the full-liquid detection position is directly detected from the conduction state between the electrodes when the voltage is applied. On the other hand, U.S. Pat. No. 5,172,140, U.S. Pat. No. 5,745,134 and U.S. Pat. No. 6,203,138 (corresponding to Japanese Patent Application laid-open No. H04-45953) and Japanese Patent Application laid-open No. 2006-95820 each disclose a technique in which an amount of the waste liquid absorbed in the absorbing body is estimated from an amount of the liquid discharged when purge, flushing, etc. is/are performed for a liquid droplet jetting head and from the number of time of the purge, flushing, etc.; and the full liquid state of the absorbing body is judged based on the presumption.
In a case that the full liquid state is detected from the conduction state between the electrodes as in Japanese Patent Application laid-open No. H08-104014 and Japanese Patent Application laid-open No. 2002-283588, the detection cannot be performed in some cases if the conductivity of the liquid is low. For example, in such a case that a liquid having a conductivity considerably lower than an assumed or predetermined conductivity is used, the full liquid state of the absorbing body cannot be detected and thus there is a fear that the waste liquid might eventually overflow.
On the other hand, in a case that the amount of the waste liquid is estimated as in U.S. Pat. No. 5,172,140, U.S. Pat. No. 5,745,134 and U.S. Pat. No. 6,203,138 (corresponding to Japanese Patent Application laid-open No. H04-45953) and Japanese Patent Application laid-open No. 2006-95820, it is possible to make judgment regarding the full liquid state regardless of the conductivity of the liquid. It is difficult, however, to correctly or accurately estimate the ratio of evaporation of the liquid due to the usage environment such as ambient temperature, humidity, etc., and a flow passage for the liquid, etc., and it is not possible to detect the full liquid state of the absorbing body such as a foam highly precisely. Therefore, it is necessary to set a large margin for the estimated value so as to prevent the waste liquid from overflowing, and there is a such a problem that a detection of “full liquid state” is given even if any non-absorb portion is remained in the absorbing body.